Beat-frequency heterodyne receiver arrangement



Nov. I2, 1929. w. KUNZE 1,735,171

BEAT FREQUENCY HETERODYNE RECEIVER ARRANGEMENT Filed D80. 18, 1926 ZOO OSCILLATOR BEAT FREQUENCY (METERS) ETHIIIIIIIIIIIIIIIIIII :llmlllll llllllllllllllllllIHHH Illlllllllflllllll CONDNSR IN Tu/Yeo CIRCUIT FOR INCOMING' w/wa canon/saris 1H INTERMEDIATE BEAT- FREQUENCY AMPLIFIER CONDENSER INA c/ cun's. osc/LLA'rmH CIRCUIT.

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CONTROL KN B FOR OSCILLATIO I CIRCUIT INVENTOR WALTER KUNZE ORNEY Patented Nov. 12, 1929 UNITED STATES PATENT orries WALTER KUNZE, OF BERLIN, GERMANY, ASSIGNOR TO RADIO CORPORATION OF 'AMERICA, A CORPORATION OF DELANVARE BEAT-FREQUENCY HETERODYNE RECEIVER ARRANGEMENT Application filed December 18, 1926, Serial No.l155,617, and in' Germany October 7,1325.

. An application for this invention has been filed in Germany on October 7 1925.

This invention relatesto beat frequency reception and the same, both as to its construction and mode of operation together with the objects and advantages thereof, will best. be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. l is a front view of a panel showing in what manner the several condenser knobs are arranged with respect to each other,

Fig. 2 isa plan View thereof, and

tion of the arrangement. I

In reception based upon the superheterodyne principle, it is necessary to have an oscillation circuit tuned to the incoming wave, and in addition thereto another oscillation circuit which is connected with a local oscillator and which must be so tuned that there results a definite frequency difference, so i called, intermediate or beat frequency. If for this purpose, therefore, condensers are used in which there exists a linear interrelationship between the angle of rotation and the resultant frequency, it is possible to so mount the two condensers that by rotating one of them, the second condenser may simultanenously be adjusted. A particularly simple manipulation of a superheterodyne receiver apparatus may be obtained if the spindle of the condenser whichaccomplishes' the adjustment to the incoming wave-length is provided with a concentric bore for receiving the spindle of the condenser which serves to regulate the beat frequency, the amount of relative rotation ofthe two condensers thus determining the beat frequency. 40 As shown to the left in Fig. 1, the relative position of the knob for the oscillation circuit condenser and that of the tuned circuit condenser for the incoming wave is indicated, and the beat frequency reading is indicated 45 by the calibrated scale on the condenser head terms of wavelength of the incoming wave.

Manipulation becomes particularly simple and easy on account of the fact that the beat frequency is adjusted at will by turning the upper condenser knob (oscillator) upon the scale of the lower condenser knob (for incoming wave), whereupon the combination or system is tuned to the wave to be received according to the calibration provided therefor. Fig. 3 is a schematic sketch in plan eleva Another point in connection with superheterodyne reception is to amplify the intermediate or beat frequency by a beat-frequency amplifier. This is ordinarily effected by the use of a transformer-coupled radio frequency.amplifier whose grid circuits'are tunable by the aid of rotarycondensers. Now, if the rotary condensers required therefor are seated upon a joint spindle whose knob is shown on theright-hand side in Fig. 1, then the entire beat frequency amplifier can be adjusted or tuned to the desired beat frequency by one manipulation. F or this purpose a calibration of the scale in terms of wave length or frequencies is also provided. The variation or variability of the beat frequency offers this great advantage, that in the pres- 7 once of any interfering transmitters, the beat frequency can be changed lmmedlately so that operations can be liberated from such disturbing actions. It has been found in the case of superhetcrodyne receivers which are set to a definite beat frequency that they are often troubled by stations whichhappen to transmit on a wave equal to this beat fre quency. Without the provision of the jointlyadjustable condensers, in the case of a three-stage beat-frequency amplifier, for example, it would be necessary to tune consecutivelyfthree condensersto the desired beat frequency; W'here circuits involving feeble damping are concerned, this is attended with serious ditficulties seeing that the tuning must be very sharp in order that an adequately large amplification may be attained. Hence, the operating knobs according to the disclosures of this invention are reduced to one knob.

Further, in the attempt to locate a certain station, it has heretofore been necessary to simultanenously manipulate the condenser for the incoming Wave and the heterodyne (local-oscillator) condenser. But according to the invention this manipulation is also reduced to the operation of a single knob. In case of variation of the beat frequency, ease of manipulation is preserved by the useoi calibrated scales.

Having thus claim:

1. In a superheterodyne receiving system, a dial for indicating the incoming signal frequency, a calibrated scale of intermediate beat-frequencies carried by said dial, and a rotary knob, controlling the local oscillator frequency, having an index, arranged to slide over said calibrated scale to indicate directly described my invention, I

the intermediate beat-frequency resulting from the conjoint action between the incoming signal frequency and the local oscillator frequency.

2. In a s'uperheterodyne receiving system having a rotary condenser for tuning the in-- put circuit to the incoming Wave, a rotary condenser for controlling the frequency of the local oscillator circuit, a dial having a calibrated scale of intermediate beat-fraquencies thereon operatively connected with the incoming Wave condenser for adjusting the same and indicating the Wave to be received, and a rotary knob, controlling the oscillator condenser, having an index, arranged to slide over the calibrated scale to indicate directly thereon the intermediate beat-frequency resulting from the conjoint action between the input circuit and the oscillator circuit.

3. In a superheterodyne receiving system having an input circuit and a local oscillator circuit for producing intermediate beat-trequencies, a rotary'conden'ser'for tuning the input circuit, a second rotary condenser for tuning the local oscillator circuit, a dial operatively connected With said first, condenser for adjusting said condenser to the incoming Wave, and a dial, operatively connected with said second condenser, having an index,and

rotatable on said first dial for adjusting the second condenser relative to the first to obtain the desired beat-frequency.

4. In a superheterodyne receiving system having an input circuit and a local oscillator circuit for producing intermediate beat-frequencies and a plurality of beat-frequency amplifier circuits, in combination, a rotary condenser for tuning-the input circuit, a sec- 0nd rotary condenser tortuning the local os- 

